P0519Generic code

P0519 Code: Idle Air Control System Performance

The P0519 code means the idle air control valve responds electrically, but the result is not what the computer expects. It can cause a rough or high idle, or an engine that stalls. Carbon buildup in the valve and the air passages is the most frequent cause.

Severity
Medium
Can I keep driving?
Yes, but with caution
Estimated cost
$40 to $350
Difficulty
Medium
System
Idle and Speed Control
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0519 code means

On engines with a throttle cable, the idle air control (IAC) valve lets air bypass the throttle plate so the engine holds a steady idle when loads come on (air conditioning, power steering, lights) or when the engine is cold. On electronic throttles, the throttle body itself does that job.

The computer watches the control circuit from its own driver transistor. The P0519 code is set when the component responds electrically but the result is not what was expected. Before you replace the part, check the fuse, relay, connector and wiring, because those are the most common causes.

Carbon buildup is enemy number one here. It clogs the valve and the air passages, and a lot of the time the problem goes away after you clean the valve and the throttle body with the right cleaner. After that, an idle relearn procedure is usually needed.

This kind of fault rarely shows up with a multimeter, because everything looks electrically correct. You have to compare what the part says against reality: with a gauge, a thermometer, a tachometer, or by commanding the component with the scan tool and seeing whether the physical result matches the command.

P0519 code symptoms

  • Check engine light or another warning light on.
  • Rough idle, high idle, or an engine that stalls.
  • Idle that hunts, rising and falling on its own.
  • The engine stalls when you come to a stop or when you turn on the air conditioning.
  • Very high idle speed.

Likely causes of the P0519 code

  1. Carbon in the valve or the passages. The most frequent cause.
  2. Vacuum leak. The valve cannot make up for it.
  3. Worn valve motor. It cannot reach the commanded position.
  4. Throttle plate out of adjustment. Someone moved the stop screw.

How to diagnose the P0519 code step by step

  1. Command the component with the scan tool and check whether it responds.
  2. Check the fuse and relay. Measure voltage on both sides of the fuse, and swap the relay with an identical one.
  3. Measure the supply at the connector. You should see battery voltage with the key on or when the component is commanded.
  4. Measure the component resistance and compare it with the manual. Also check its insulation to ground.
  5. Check the control wire for continuity all the way to the computer and for any short.
  6. Clean the valve and the throttle body and repeat the test.
  7. Perform the idle relearn according to the manufacturer.

How to fix the P0519 code

  • Repair the connector, the wiring or the supply.
  • Replace the idle air control valve if it does not respond when it gets a correct supply and command.
  • Clear the codes and verify the repair.

Technical reference data

  • Stepper motor valve (4 or 6 wires) or rotary valve (2 or 3 wires).
  • Typical hot idle speed: 650 to 850 rpm.
  • These values are a general guide: check the manufacturer data for your vehicle.

Brand-specific notes

This code is very common on cable-throttle engines. Clean the valve and the throttle body and look for vacuum leaks before you replace anything.

P0519 on Honda

Very common on Honda engines with a throttle cable.

P0519 on Nissan

Very common on Nissan engines with a throttle cable.

P0519 on GM

Very common on GM engines with a throttle cable.

P0519 on Chrysler

Very common on Chrysler engines with a throttle cable.

Frequently asked questions about P0519

What does the P0519 code mean?
It is a generic OBD2 code that means the idle air control valve responds electrically, but the result is not what the computer expects. The valve may be clogged, worn, or fighting a vacuum leak.
Can I drive with a P0519 code?
Yes, but with caution. A rough idle or a stall at a stop sign can be a hazard in traffic, so get it checked soon.
What does the idle air control valve do?
On engines with a throttle cable, the IAC valve lets air bypass the throttle plate so the engine holds a steady idle when loads come on (air conditioning, power steering, lights) or when the engine is cold. On electronic throttles, the throttle body itself does that job.
Do I always have to replace the part?
No. Check the fuses, relays, connectors and wiring first. Carbon is also very common here, and cleaning often solves it.
How much does it cost to fix P0519?
As a rough guide, between $40 and $350. A cleaning is at the low end, and a new valve with labor is at the high end.
Will a P0519 code clear itself?
Rarely. Carbon and a worn motor do not fix themselves, so the P0519 code usually comes back until the valve is cleaned or replaced.
What is the most common cause of P0519?
Carbon in the valve or in the air passages. A vacuum leak, a worn valve motor and a throttle plate stop screw that was moved are the next most likely causes.

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